No. 386.] REVIEWS OF RECENT LITERATURE, 179 
These rocks are intruded by redbiotite-granite, diorite, norite, ser- 
pentine and gray granite. The mica-schist is regarded as a meta- 
morphosed sediment. Under the sediments, but above the archean 
granites and gneisses, is the gray banded Fordham gneiss composed 
of alternating quartzose and biotite bands and injected parallel to 
the banding by pegmatite or granite. This, it is thought, may be 
an Algonkian sediment. The Yonker’s gneiss, which in an earlier 
article the writer concluded to be a metamorphosed sediment is now 
thought to be an intrusive. All the serpentines of the district are 
also believed to have been derived from igneous rocks. 
